1. Field of the Invention
The present invention relates generally to a mobile terminal enabled with a Bluetooth function, and in particular, to a method of connecting a mobile terminal enabled with a Bluetooth function and a Bluetooth access point (AP) that provides a wired/wireless communication interface by controlling a short-distance communication connection of the mobile terminal.
2. Description of the Related Art
Bluetooth is a short-distance wireless communication technology of wirelessly transmitting information such as text, voice, and/or video data within a range of 10 to 100 m at up to 1 Mbps.
A Bluetooth-enabled device (hereinafter, referred to as a Bluetooth device) enters a connect state for communication with other Bluetooth devices through the states of inquiry, inquiry scan, page, and page scan. In this process, the Bluetooth devices are designated as a master and slaves according to their roles.
To establish a new connection between Bluetooth devices within the range of each other, the devices must coincide in operation clock and frequency pattern. In the inquiry state, a master repeatedly transmits signals at an operation frequency to let slaves synchronize to the frequency pattern. In the inquiry scan process, the slaves detect the operation frequency and synchronize to it. In the page state, the master transmits a clock signal that enables the slaves to synchronize to the operation clock of the master. The slaves detect the clock signal and synchronize to it in the page scan state. A network consisting of a master and one or more slaves connected to the master through the procedure is called “piconet”.
In accordance with the existing proposed Bluetooth technology, a Bluetooth piconet consists of one master and seven active slaves. To introduce a new slave into the piconet, the master releases one of the slaves from the active state and connects a communication to the new active slave, instead.
Operation modes between the master and the slaves are an active mode for normal communication between the master and the slaves and a hold/sniff/park mode being a low power consumption mode in the Bluetooth communication. The hold mode is a typical mode set when no data needs to be transmitted for a relatively long time. In the sniff mode, data is exchanged between the master and a slave during a preset time period. The park mode is a mode in which the master and the slave intermittently communicate with each other for the slave to maintain synchronization and request transitioning to the active state.
In any of the active, sniff, and park modes, the slave periodically performs an operation corresponding to the mode. Although the hold mode is not periodical, a hold mode operation can be considered as periodic like operations in the other modes because the slave is to wake up (is activated) at a predetermined time and communicate with the master.
When a slave connected to the master is transitioned to a particular mode, the master assigns communication times to all the slaves by negotiations with them. The slaves are configured to operate periodically in their modes by negotiations with the master. The slaves communicate with the master at the negotiated times and for the negotiated periods until their modes are changed.
An existing wireless telephone system charges a mobile terminal, such as a PCS (Personal Communications Services) or cellular phone, a higher rate than a wired telephone system. To overcome this shortcoming, a method of using the wired telephone system through a mobile terminal equipped with a Bluetooth module being a short-distance wireless communication module has been proposed. This method can be implemented via an AP that enables a data exchange between a wired network and a wireless network.
Hence, a Bluetooth standardization group has proposed standards by which a single mobile terminal can provide three different functionalities. That is, a Bluetooth-enabled mobile terminal acts as an intercom handset if it is connected to an intercom in an office, as a wireless telephone handset in a household when it is connected to a base station for a wireless telephone, and as a mobile phone when it moves.
FIG. 1 illustrates an exemplary use of a mobile terminal having a Bluetooth module built therein as a short-distance wireless communication module in a household. Referring to FIG. 1, a mobile terminal 10 including a Bluetooth module 12 built therein functions as a typical mobile phone outside a household 50. That is, the mobile terminal 10 receives a mobile telephony service from a PLMN (Public Land Mobile Network) 75 via a base station 70.
Within the household 50, however, the mobile terminal 10 functions as a wireless phone through connection to a Bluetooth AP 30 connected to an XDSL module 40 (xDSL is a generic abbreviation for the many flavors of DSL or Digital Subscriber Line technology). The Bluetooth AP 30 further wirelessly transmits and receives data to and from a Bluetooth-enabled wireless device 20, such as a camera 22 and an audio device 24, in the household 50.
The XDSL module 40, connected to a wired phone 45, allows a call to be conducted through the wired phone 45 when the mobile terminal 10 is outside the household 50. The XDSL 40 is connected to a DSLAM (Digital Subscriber Line Access Multiplexer) 60, which is in turn connected to a PSTN (Public Switched Telephone Network) 65.
To function as a wireless phone within the household 50, the Bluetooth-enabled mobile terminal 10 must establish a connection with another Bluetooth module through the inquiry, inquiry scan, page, and page scan states. Here, minimization of current consumption is the most important if the mobile terminal 10 is used for wireless communication.
In this context, methods of designing a Bluetooth-enabled mobile terminal with a minimal current consumption in a connect state have been studied. A typical current consumption method as defined in the Bluetooth specifications is to transition the mobile terminal to a park mode or a sniff mode.
Within the household 50, the mobile terminal 10 automatically attempts to connect to the Bluetooth AP 30 without user manipulation. Because the mobile terminal 10 is kept connected to the Bluetooth AP 30, tens of milliampheres of current are continuously consumed with no communication connected. Therefore, the mobile terminal 10 is automatically connected to the Bluetooth AP 30 even in an idle state when no communications are being conducted. The resulting continuous current consumption drastically reduces charged current in the mobile terminal 10.
What is worse, the conventional Bluetooth-enabled mobile terminal continuously attempts to connect to the Bluetooth AP irrespective of a place where a user wants to use the mobile terminal as a wireless phone, thereby resulting in further unnecessary current dissipation.